During fabrication, a workpiece usually is to be spun to be machined. Thus, manufacturers have developed a positioning device with a loading carrier where the workpiece is disposed. The positioning device can either rotate the loading carrier to rotate the workpiece or stop the rotation of the loading carrier to stop the rotation of the workpiece.
In terms of the positioning device, when the workpiece is rotated, for example, a hydraulic power source is input to rotate the loading carrier; when the workpiece is to be stopped, the power source is also input to drive a braking component to stop the loading carrier. However, when the loading carrier keeps in rotation and a power failure (i.e., power outage) happens accidently and immediately, the loading carrier may not stop such that the workpiece may lose control with the rotation of the lading carrier.